diff --git a/.gitignore b/.gitignore
index b5cbf6efcd7..c31896c826d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -222,6 +222,8 @@ samples/server/petstore/haskell-yesod/stack.yaml.lock
 .Rproj.user
 samples/client/petstore/R/**/petstore.Rcheck/
 samples/client/petstore/R/**/*.tar.gz
+samples/client/petstore/R/R.Rproj
+samples/client/petstore/R/man/
 
 # elixir
 samples/client/petstore/elixir/_build/
diff --git a/modules/openapi-generator/src/main/resources/r/modelAnyOf.mustache b/modules/openapi-generator/src/main/resources/r/modelAnyOf.mustache
index d3b86f23ee8..3897d549b9a 100644
--- a/modules/openapi-generator/src/main/resources/r/modelAnyOf.mustache
+++ b/modules/openapi-generator/src/main/resources/r/modelAnyOf.mustache
@@ -11,14 +11,31 @@
 {{classname}} <- R6::R6Class(
   '{{classname}}',
   public = list(
+    #' @field actual_instance the object stored in this instance.
     actual_instance = NULL,
+    #' @field actual_type the type of the object stored in this instance.
     actual_type = NULL,
+    #' @field any_of  a list of object types defined in the anyOf schema.
     any_of = list({{#anyOf}}"{{{.}}}"{{^-last}}, {{/-last}}{{/anyOf}}),
+    #' Initialize a new {{{classname}}}.
+    #'
+    #' @description
+    #' Initialize a new {{{classname}}}.
+    #'
+    #' @export
+    #' @md
     initialize = function(
-        {{#requiredVars}}`{{baseName}}`, {{/requiredVars}}{{#optionalVars}}`{{baseName}}`={{{defaultValue}}}{{^defaultValue}}NULL{{/defaultValue}}, {{/optionalVars}}...
     ) {
-      local_optional_var <- list(...)
     },
+    #' Deserialize JSON string into an instance of {{{classname}}}.
+    #'
+    #' @description
+    #' Deserialize JSON string into an instance of {{{classname}}}.
+    #'
+    #' @param input The input JSON.
+    #' @return An instance of {{{classname}}}.
+    #' @export
+    #' @md
     fromJSON = function(input) {
       error_messages <- list()
 
@@ -41,6 +58,14 @@
       # no match
       stop(paste("No match found when deserializing the payload into {{{classname}}} with anyOf schemas {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}. Details: ", paste(error_messages, collapse = ', ')))
     },
+    #' Serialize {{{classname}}} to JSON string.
+    #'
+    #' @description
+    #' Serialize {{{classname}}} to JSON string.
+    #'
+    #' @return JSON string reprenation of the {{{classname}}}.
+    #' @export
+    #' @md
     toJSON = function() {
       if (!is.null(self$actual_instance)) {
         self$actual_instance$toJSONString()
@@ -48,6 +73,15 @@
         NULL
       }
     },
+    #' Validate the input JSON with respect to {{{classname}}}.
+    #'
+    #' @description
+    #' Validate the input JSON with respect to {{{classname}}} and
+    #' throw exception if invalid.
+    #'
+    #' @param input The input JSON.
+    #' @export
+    #' @md
     validateJSON = function(input) {
       # backup current values
       actual_instance_bak <- self$actual_instance
diff --git a/modules/openapi-generator/src/main/resources/r/modelOneOf.mustache b/modules/openapi-generator/src/main/resources/r/modelOneOf.mustache
index 1e33da9e7ed..4f295c3319c 100644
--- a/modules/openapi-generator/src/main/resources/r/modelOneOf.mustache
+++ b/modules/openapi-generator/src/main/resources/r/modelOneOf.mustache
@@ -11,14 +11,30 @@
 {{classname}} <- R6::R6Class(
   '{{classname}}',
   public = list(
+    #' @field actual_instance the object stored in this instance.
     actual_instance = NULL,
+    #' @field actual_type the type of the object stored in this instance.
     actual_type = NULL,
+    #' @field one_of  a list of object types defined in the oneOf schema.
     one_of = list({{#oneOf}}"{{{.}}}"{{^-last}}, {{/-last}}{{/oneOf}}),
-    initialize = function(
-        {{#requiredVars}}`{{baseName}}`, {{/requiredVars}}{{#optionalVars}}`{{baseName}}`={{{defaultValue}}}{{^defaultValue}}NULL{{/defaultValue}}, {{/optionalVars}}...
-    ) {
-      local_optional_var <- list(...)
+    #' Initialize a new {{{classname}}}.
+    #'
+    #' @description
+    #' Initialize a new {{{classname}}}.
+    #'
+    #' @export
+    #' @md
+    initialize = function() {
     },
+    #' Deserialize JSON string into an instance of {{{classname}}}.
+    #'
+    #' @description
+    #' Deserialize JSON string into an instance of {{{classname}}}.
+    #'
+    #' @param input The input JSON.
+    #' @return An instance of {{{classname}}}.
+    #' @export
+    #' @md
     fromJSON = function(input) {
       matched <- 0 # match counter
       matched_schemas <- list() #names of matched schemas
@@ -56,6 +72,14 @@
 
       self
     },
+    #' Serialize {{{classname}}} to JSON string.
+    #'
+    #' @description
+    #' Serialize {{{classname}}} to JSON string.
+    #'
+    #' @return JSON string reprenation of the {{{classname}}}.
+    #' @export
+    #' @md
     toJSON = function() {
       if (!is.null(self$actual_instance)) {
         self$actual_instance$toJSONString()
@@ -63,6 +87,15 @@
         NULL
       }
     },
+    #' Validate the input JSON with respect to {{{classname}}}.
+    #'
+    #' @description
+    #' Validate the input JSON with respect to {{{classname}}} and
+    #' throw exception if invalid.
+    #'
+    #' @param input The input JSON.
+    #' @export
+    #' @md
     validateJSON = function(input) {
       # backup current values
       actual_instance_bak <- self$actual_instance
diff --git a/modules/openapi-generator/src/main/resources/r/partial_header.mustache b/modules/openapi-generator/src/main/resources/r/partial_header.mustache
index 5c70b65ef06..e3282fc9713 100644
--- a/modules/openapi-generator/src/main/resources/r/partial_header.mustache
+++ b/modules/openapi-generator/src/main/resources/r/partial_header.mustache
@@ -1,15 +1,16 @@
 {{#appName}}
-# {{{.}}}
-#
+#' {{{.}}}
+#'
 {{/appName}}
 {{#appDescription}}
-# {{{.}}}
-#
+#' {{{.}}}
+#'
 {{/appDescription}}
 {{#version}}
-# The version of the OpenAPI document: {{{.}}}
+#' The version of the OpenAPI document: {{{.}}}
 {{/version}}
 {{#infoEmail}}
-# Contact: {{{.}}}
+#' Contact: {{{.}}}
 {{/infoEmail}}
-# Generated by: https://openapi-generator.tech
+#' Generated by: https://openapi-generator.tech
+#'
diff --git a/samples/client/petstore/R/R/allof_tag_api_response.R b/samples/client/petstore/R/R/allof_tag_api_response.R
index 8b83a920cfb..6141dc37413 100644
--- a/samples/client/petstore/R/R/allof_tag_api_response.R
+++ b/samples/client/petstore/R/R/allof_tag_api_response.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title AllofTagApiResponse
diff --git a/samples/client/petstore/R/R/animal.R b/samples/client/petstore/R/R/animal.R
index b330b10a1b4..86e043d62f6 100644
--- a/samples/client/petstore/R/R/animal.R
+++ b/samples/client/petstore/R/R/animal.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Animal
diff --git a/samples/client/petstore/R/R/any_of_pig.R b/samples/client/petstore/R/R/any_of_pig.R
index d4e5fffe068..130e27c6ed6 100644
--- a/samples/client/petstore/R/R/any_of_pig.R
+++ b/samples/client/petstore/R/R/any_of_pig.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title AnyOfPig
@@ -18,14 +19,31 @@
 AnyOfPig <- R6::R6Class(
   'AnyOfPig',
   public = list(
+    #' @field actual_instance the object stored in this instance.
     actual_instance = NULL,
+    #' @field actual_type the type of the object stored in this instance.
     actual_type = NULL,
+    #' @field any_of  a list of object types defined in the anyOf schema.
     any_of = list("BasquePig", "DanishPig"),
+    #' Initialize a new AnyOfPig.
+    #'
+    #' @description
+    #' Initialize a new AnyOfPig.
+    #'
+    #' @export
+    #' @md
     initialize = function(
-        `className`, `color`, `size`, ...
     ) {
-      local_optional_var <- list(...)
     },
+    #' Deserialize JSON string into an instance of AnyOfPig.
+    #'
+    #' @description
+    #' Deserialize JSON string into an instance of AnyOfPig.
+    #'
+    #' @param input The input JSON.
+    #' @return An instance of AnyOfPig.
+    #' @export
+    #' @md
     fromJSON = function(input) {
       error_messages <- list()
 
@@ -60,6 +78,14 @@ AnyOfPig <- R6::R6Class(
       # no match
       stop(paste("No match found when deserializing the payload into AnyOfPig with anyOf schemas BasquePig, DanishPig. Details: ", paste(error_messages, collapse = ', ')))
     },
+    #' Serialize AnyOfPig to JSON string.
+    #'
+    #' @description
+    #' Serialize AnyOfPig to JSON string.
+    #'
+    #' @return JSON string reprenation of the AnyOfPig.
+    #' @export
+    #' @md
     toJSON = function() {
       if (!is.null(self$actual_instance)) {
         self$actual_instance$toJSONString()
@@ -67,6 +93,15 @@ AnyOfPig <- R6::R6Class(
         NULL
       }
     },
+    #' Validate the input JSON with respect to AnyOfPig.
+    #'
+    #' @description
+    #' Validate the input JSON with respect to AnyOfPig and
+    #' throw exception if invalid.
+    #'
+    #' @param input The input JSON.
+    #' @export
+    #' @md
     validateJSON = function(input) {
       # backup current values
       actual_instance_bak <- self$actual_instance
diff --git a/samples/client/petstore/R/R/api_client.R b/samples/client/petstore/R/R/api_client.R
index 299da075124..f18d3bfc88a 100644
--- a/samples/client/petstore/R/R/api_client.R
+++ b/samples/client/petstore/R/R/api_client.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 
 #' ApiClient Class
diff --git a/samples/client/petstore/R/R/basque_pig.R b/samples/client/petstore/R/R/basque_pig.R
index 054582a1daa..3534bd2cc5c 100644
--- a/samples/client/petstore/R/R/basque_pig.R
+++ b/samples/client/petstore/R/R/basque_pig.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title BasquePig
diff --git a/samples/client/petstore/R/R/cat.R b/samples/client/petstore/R/R/cat.R
index 0c265ae99f0..97c75ad6135 100644
--- a/samples/client/petstore/R/R/cat.R
+++ b/samples/client/petstore/R/R/cat.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Cat
diff --git a/samples/client/petstore/R/R/cat_all_of.R b/samples/client/petstore/R/R/cat_all_of.R
index 60abcbbbf3b..6b5478aba50 100644
--- a/samples/client/petstore/R/R/cat_all_of.R
+++ b/samples/client/petstore/R/R/cat_all_of.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title CatAllOf
diff --git a/samples/client/petstore/R/R/category.R b/samples/client/petstore/R/R/category.R
index 49259ef6848..3fbe15d1d22 100644
--- a/samples/client/petstore/R/R/category.R
+++ b/samples/client/petstore/R/R/category.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Category
diff --git a/samples/client/petstore/R/R/danish_pig.R b/samples/client/petstore/R/R/danish_pig.R
index 64482f7d04a..9f6ec81b004 100644
--- a/samples/client/petstore/R/R/danish_pig.R
+++ b/samples/client/petstore/R/R/danish_pig.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title DanishPig
diff --git a/samples/client/petstore/R/R/dog.R b/samples/client/petstore/R/R/dog.R
index e06e313aef3..b94645612f3 100644
--- a/samples/client/petstore/R/R/dog.R
+++ b/samples/client/petstore/R/R/dog.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Dog
diff --git a/samples/client/petstore/R/R/dog_all_of.R b/samples/client/petstore/R/R/dog_all_of.R
index 3fbe701923e..bb7eabb456d 100644
--- a/samples/client/petstore/R/R/dog_all_of.R
+++ b/samples/client/petstore/R/R/dog_all_of.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title DogAllOf
diff --git a/samples/client/petstore/R/R/fake_api.R b/samples/client/petstore/R/R/fake_api.R
index 46e377cb8f6..c1cf274f9a0 100644
--- a/samples/client/petstore/R/R/fake_api.R
+++ b/samples/client/petstore/R/R/fake_api.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Fake operations
diff --git a/samples/client/petstore/R/R/model_api_response.R b/samples/client/petstore/R/R/model_api_response.R
index cee53f1529b..1d7ce8238c1 100644
--- a/samples/client/petstore/R/R/model_api_response.R
+++ b/samples/client/petstore/R/R/model_api_response.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title ModelApiResponse
diff --git a/samples/client/petstore/R/R/order.R b/samples/client/petstore/R/R/order.R
index 966e4e0fa77..958a4836c8f 100644
--- a/samples/client/petstore/R/R/order.R
+++ b/samples/client/petstore/R/R/order.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Order
diff --git a/samples/client/petstore/R/R/pet.R b/samples/client/petstore/R/R/pet.R
index d02690d24aa..f26d36da4b9 100644
--- a/samples/client/petstore/R/R/pet.R
+++ b/samples/client/petstore/R/R/pet.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Pet
diff --git a/samples/client/petstore/R/R/pet_api.R b/samples/client/petstore/R/R/pet_api.R
index 3045dd77dfb..03379a27abc 100644
--- a/samples/client/petstore/R/R/pet_api.R
+++ b/samples/client/petstore/R/R/pet_api.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Pet operations
diff --git a/samples/client/petstore/R/R/pig.R b/samples/client/petstore/R/R/pig.R
index 5afa7dc8943..65c24ce7408 100644
--- a/samples/client/petstore/R/R/pig.R
+++ b/samples/client/petstore/R/R/pig.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Pig
@@ -18,14 +19,30 @@
 Pig <- R6::R6Class(
   'Pig',
   public = list(
+    #' @field actual_instance the object stored in this instance.
     actual_instance = NULL,
+    #' @field actual_type the type of the object stored in this instance.
     actual_type = NULL,
+    #' @field one_of  a list of object types defined in the oneOf schema.
     one_of = list("BasquePig", "DanishPig"),
-    initialize = function(
-        `className`, `color`, `size`, ...
-    ) {
-      local_optional_var <- list(...)
+    #' Initialize a new Pig.
+    #'
+    #' @description
+    #' Initialize a new Pig.
+    #'
+    #' @export
+    #' @md
+    initialize = function() {
     },
+    #' Deserialize JSON string into an instance of Pig.
+    #'
+    #' @description
+    #' Deserialize JSON string into an instance of Pig.
+    #'
+    #' @param input The input JSON.
+    #' @return An instance of Pig.
+    #' @export
+    #' @md
     fromJSON = function(input) {
       matched <- 0 # match counter
       matched_schemas <- list() #names of matched schemas
@@ -76,6 +93,14 @@ Pig <- R6::R6Class(
 
       self
     },
+    #' Serialize Pig to JSON string.
+    #'
+    #' @description
+    #' Serialize Pig to JSON string.
+    #'
+    #' @return JSON string reprenation of the Pig.
+    #' @export
+    #' @md
     toJSON = function() {
       if (!is.null(self$actual_instance)) {
         self$actual_instance$toJSONString()
@@ -83,6 +108,15 @@ Pig <- R6::R6Class(
         NULL
       }
     },
+    #' Validate the input JSON with respect to Pig.
+    #'
+    #' @description
+    #' Validate the input JSON with respect to Pig and
+    #' throw exception if invalid.
+    #'
+    #' @param input The input JSON.
+    #' @export
+    #' @md
     validateJSON = function(input) {
       # backup current values
       actual_instance_bak <- self$actual_instance
diff --git a/samples/client/petstore/R/R/store_api.R b/samples/client/petstore/R/R/store_api.R
index 64a85f6fddd..be830ad14d7 100644
--- a/samples/client/petstore/R/R/store_api.R
+++ b/samples/client/petstore/R/R/store_api.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Store operations
diff --git a/samples/client/petstore/R/R/tag.R b/samples/client/petstore/R/R/tag.R
index bbddb9ec088..9bbbd8fbf65 100644
--- a/samples/client/petstore/R/R/tag.R
+++ b/samples/client/petstore/R/R/tag.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title Tag
diff --git a/samples/client/petstore/R/R/update_pet_request.R b/samples/client/petstore/R/R/update_pet_request.R
index dcd957d2380..b6c5b8886e5 100644
--- a/samples/client/petstore/R/R/update_pet_request.R
+++ b/samples/client/petstore/R/R/update_pet_request.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title UpdatePetRequest
diff --git a/samples/client/petstore/R/R/user.R b/samples/client/petstore/R/R/user.R
index ba27b8d8495..f5ba491a774 100644
--- a/samples/client/petstore/R/R/user.R
+++ b/samples/client/petstore/R/R/user.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title User
diff --git a/samples/client/petstore/R/R/user_api.R b/samples/client/petstore/R/R/user_api.R
index 8ac0f4d37dd..81f492ff4a8 100644
--- a/samples/client/petstore/R/R/user_api.R
+++ b/samples/client/petstore/R/R/user_api.R
@@ -1,9 +1,10 @@
-# OpenAPI Petstore
-#
-# This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
-#
-# The version of the OpenAPI document: 1.0.0
-# Generated by: https://openapi-generator.tech
+#' OpenAPI Petstore
+#'
+#' This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+#'
+#' The version of the OpenAPI document: 1.0.0
+#' Generated by: https://openapi-generator.tech
+#'
 
 #' @docType class
 #' @title User operations
diff --git a/samples/client/petstore/R/build_and_test.bash b/samples/client/petstore/R/build_and_test.bash
index 3482f3d083d..2079f75da03 100644
--- a/samples/client/petstore/R/build_and_test.bash
+++ b/samples/client/petstore/R/build_and_test.bash
@@ -17,6 +17,7 @@ Rscript -e "install.packages('R6', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('base64enc', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('rlang', repos='$REPO', lib='$R_LIBS_USER')"
 Rscript -e "install.packages('rjson', repos='$REPO', lib='$R_LIBS_USER')"
+Rscript -e "install.packages('devtools', repos='$REPO', lib='$R_LIBS_USER')"
 
 rm petstore_1.0.0.tar.gz || true